1. Field of the Invention
The present invention relates in general to land vehicles, and in particular to agricultural vehicles and systems associated with such agricultural vehicles. Specifically, the present invention relates to a marking system for indicating the boundaries of an area treated by an agricultural vehicle.
2. Description of the Prior Art.
Modern agricultural science includes the treatment of large areas for many reasons, such as applying fertilizers, herbicides, insecticides and the like. For many reasons, including economy, ecology, efficiency and maximized coverage, it is important that the area being treated be clearly marked to distinguish the areas that have already been treated from the areas that have not yet been treated.
For this reason, there have been several proposals for systems that demark and identify areas of treatment by various agricultural techniques and processes. Some of these proposals have included mechanical demarcation devices, and some of the proposals have included spraying marking foam to form the marking system.
No matter what design is used, however, there are certain requirements that should be met to ensure that the marking system is effective for the intended purpose.
For example, the marking system should be amenable to efficient operation by a minimum number of people. It is this requirement that often presents drawbacks to the mechanical systems.
Still further, the marking system should not, itself, be a source of crop damage. Here, also, the mechanical systems have been found lacking.
The agricultural marking system will be subject to many conditions that may change within a single operation and may also change from operation to operation. In order to be most effective, the marking system should be amenable to producing a clear marking system under all sorts of conditions which may be subject to change even within a single application.
While mechanical systems involving placement of stakes or the like may be somewhat amenable to providing a clear marking system each time, such systems are so wasteful of manpower and may be so time consuming as to make them economically undesirable. Coupled with the other disadvantages of such systems, mechanical marking systems do not appear to be a viable way of effecting the marking of areas of treatment.
In view of the shortcomings of mechanical systems, there have been several proposals for nonmechanical marking systems. These nonmechanical systems generally involve the use of marking foam that is sprayed onto the area behind a motor vehicle.
While somewhat effective in overcoming the justmentioned drawbacks associated with mechanical marking systems, the present foam spraying systems have their own drawbacks.
Chief among such drawbacks results from the lack of adaptability for these systems. That is, the marking systems that spray foam onto an area to demark that area are subject to producing results of varying effectiveness as conditions change.
For example, as discussed above, it is necessary for the marking system to provide a clearly evident mark over the entire range of the area being treated. This mark should not deteriorate to a level that it cannot be easily seen by workers at a later time whereby an already-treated area is re-treated because the markings were not evident enough. Clearly, to ensure such a situation does not exist, the marking foam can be made dark and thick enough to compensate for such a later deterioration of marking foam. However, such a solution may prove wasteful of marking foam by making some areas too dark in order to ensure that other areas have marks that are dark enough to be easily seen. This problem of nonevident markings may also occur at or near the end of a run when the supply of marking foam-producing material is nearly exhausted.
Another problem associated with the lack of adaptability of present foam marking systems occurs when conditions of a run change from earlier conditions within that run or from conditions existing in a prior run. System settings may make the marking acceptable for the earlier-existing conditions, but not for the later-encountered conditions. This can also be a result of portions of the dispensing system functioning differently at different times, for example due to clogging or the like. Present systems really do not have any effective method for accounting for such variation in operating conditions, and thus, nonuniform markings may result from the present systems which mark using foam which is applied using a spray system.
Still further, in order to be most effective, that portion of the overall system directed to fluid storage should be designed specifically for fluid storage, and that portion of the overall system directed to marking foam production should be designed for such operation. However, in most of the present systems, one tank is used to both store and make the marking foam. This requires such a tank to balance design considerations whereby some storage-related functions may be less efficient in order to make foam-making functions viable and vice versa. System maintenance and cleaning may be difficult in such systems as well.
Since the final foam-marking product may be dependent on the ratio of the various components used to form that marking foam and the conditions under which it is formed, to be most effective, the overall system should include some means for controlling and varying such parameters as necessary. However, present systems generally make the marking foam in a single tank and then dispense that foam using nozzles or the like. There is no means for varying the conditions or the ratios, or both, associated with the making and the dispensing of the final foam-marking product. Therefore, the final product in most of the present systems may not have the proper quality to be most effective for a particular application.
A still further drawback to present systems is the use of a pump for moving foam through the system. It may be more efficient to move liquid or a mixture of liquid and foaming agent by some means, and then to move marking foam using a motive means that is most efficient in moving such fluids. Present marking foam systems do not make this distinction in fluid properties and thus, may not be efficient as possible.
Therefore, while present marking systems that use marking foam are successful in overcoming some drawbacks associated with other systems, the nonadaptability and lack of efficient foam-forming and moving means of such foam marking systems may create problems that tend to vitiate the overall performance of such systems.
Accordingly, there is a need for marking system that uses marking foam, but which is adaptable and amenable to changing operation to account for changing conditions to produce effective markings for all conditions to which the system may be exposed, and which can be designed to be most efficient in its overall operation.